ccdconfig(8)

NAME

ccdconfig - configuration utility for the concatenated disk

driver

SYNOPSIS

ccdconfig [-cv] ccd ileave [flags] dev ...
ccdconfig -C [-v] [-f config_file]
ccdconfig -u [-v] ccd ...
ccdconfig -U [-v] [-f config_file]
ccdconfig -g [ccd ...]

DESCRIPTION

The ccdconfig utility is used to dynamically configure and

unconfigure
concatenated disk devices, or ccds. For more information

about the ccd,
see ccd(4).

The options are as follows:

-c Configure a ccd. This is the default behavior of

ccdconfig.

-C Configure all ccd devices listed in the ccd configu

ration file.

-f config_file

When configuring or unconfiguring all devices, read

the file
config_file instead of the default /etc/ccd.conf.

-g Dump the current ccd configuration in a format suit

able for use

as the ccd configuration file. If no arguments are

specified,
every configured ccd is dumped. Otherwise, the con

figuration of
each listed ccd is dumped.

-u Unconfigure a ccd.

-U Unconfigure all ccd devices listed the ccd configu

ration file.

-v Cause ccdconfig to be verbose.

A ccd is described on the command line and in the ccd con

figuration file
by the name of the ccd, the interleave factor, the ccd con

figuration
flags, and a list of one or more devices. The flags may be

represented
as a decimal number, a hexadecimal number, a comma-separated

list of
strings, or the word ``none''. The flags are as follows:

CCDF_UNIFORM 0x02 Use uniform interleave
CCDF_MIRROR 0x04 Support mirroring

The format in the configuration file appears exactly as if

it were
entered on the command line. Note that on the command line

and in the
configuration file, the flags argument is optional.

#
# /etc/ccd.conf
# Configuration file for concatenated disk devices
#

# ccd ileave flags component devices
ccd0 16 none /dev/da2s1 /dev/da3s1

The component devices need to name partitions of type FS_BS

DFFS (or
``4.2BSD'' as shown by disklabel(8)).

FILES

/etc/ccd.conf default ccd configuration file

EXAMPLES

A number of ccdconfig examples are shown below. The argu

ments passed to
ccdconfig are exactly the same as you might place in the

/etc/ccd.conf
configuration file. The first example creates a 4-disk

stripe out of
four scsi disk partitions. The stripe uses a 64 sector in

terleave. The
second example is an example of a complex stripe/mirror com

bination. It
reads as a two disk stripe of da4 and da5 which is mirrored

to a two disk
stripe of da6 and da7. The last example is a simple mirror.

The 2nd
slice of /dev/da8 is mirrored with the 3rd slice of /dev/da9

and assigned
to ccd0.

# ccdconfig ccd0 64 none /dev/da0s1 /dev/da1s1 /dev/da2s1

/dev/da3s1
# ccdconfig ccd0 128 CCDF_MIRROR /dev/da4 /dev/da5 /dev/da6

/dev/da7
# ccdconfig ccd0 128 CCDF_MIRROR /dev/da8s2 /dev/da9s3

When you create a new ccd disk you generally want to

fdisk(8) and
disklabel(8) it before doing anything else. Once you create

the initial
label you can edit it, adding additional partitions. The

label itself
takes up the first 16 sectors of the ccd disk. If all you

are doing is
creating file systems with newfs, you do not have to worry

about this as
newfs will skip the label area. However, if you intend to

dd(1) to or
from a ccd partition it is usually a good idea to construct

the partition
such that it does not overlap the label area. For example,

if you have A
ccd disk with 10000 sectors you might create a 'd' partition

with offset
16 and size 9984.

# disklabel ccd0 > /tmp/disklabel.ccd0
# disklabel -Rr ccd0 /tmp/disklabel.ccd0
# disklabel -e ccd0

The disklabeling of a ccd disk is usually a one-time affair.

If you
reboot the machine and reconfigure the ccd disk, the diskla

bel you had
created before will still be there and not require reini

tialization.
Beware that changing any ccd parameters: interleave, flags,

or the device
list making up the ccd disk, will usually destroy any prior

data on that
ccd disk. If this occurs it is usually a good idea to

reinitialize the
label before [re]constructing your ccd disk.

RECOVERY

An error on a ccd disk is usually unrecoverable unless you

are using the
mirroring option. But mirroring has its own perils: It as

sumes that both
copies of the data at any given sector are the same. This

holds true
until a write error occurs or until you replace either side

of the mirror. This is a poor-man's mirroring implementation. It

works well
enough that if you begin to get disk errors you should be

able to backup
the ccd disk, replace the broken hardware, and then regener

ate the ccd
disk. If you need more than this you should look into ex

ternal hardware
RAID SCSI boxes, RAID controllers (see GENERIC), or software

RAID systems
such as geom(8) and vinum(8).

SEE ALSO

dd(1), ccd(4), disklabel(8), fdisk(8), rc(8), vinum(8)

HISTORY

The ccdconfig utility first appeared in NetBSD 1.0A.

BUGS

The initial disklabel returned by ccd(4) specifies only 3

partitions.
One needs to change the number of partitions to 8 using

``disklabel -e''
to get the usual BSD expectations.

BSD July 17, 1995

BSD